1. Field of the Invention
The invention relates generally to a seal and, more particularly, to an annular seal for use with an annular piston included in a hydraulic system which may be used to actuate a disc brake assembly.
2. Related Art
As known in the art, dry friction brakes are subject to contamination due to exposure to the vehicles environment, and are also prone to excessive heat build up due to the frictional interaction among components. Each of these factors may adversely affect the service life of the brake assembly. Disc brake assemblies in which the discs are bathed in a coolant fluid, commonly referred to as wet disc brake assemblies, are known in the art and have been used in certain applications to overcome the aforementioned problems associated with dry friction brakes. However, the use of wet disc brakes in certain applications has heretofore been limited due to spacial considerations. For instance, the envelope of prior wet disc brake assemblies may adversely impact the scrub radius and kingpin inclination angle of an associated steerable axle assembly. In a known wet disc brake system, the interleaved discs of the brake assembly are actuated by an annular piston which is sealed at one location to a housing surrounding the piston by an annular seal disposed in a groove formed in the piston. This arrangement is typical of many piston applications which include seals such as O-rings disposed in an annular groove formed in the piston. In certain applications, the radial thickness of the piston annulus may be insufficient, or too small, to accept a convention O-ring groove. The increase in the piston annulus which would be required to accept an O-ring groove may be unacceptable since such an increase in thickness would result in an increase in the volumetric displacement of fluid as the piston is actuated, which in turn may require an undesirable addition of an accumulator in the vehicle fluid system. Accordingly, automotive design engineers continue to search for novel means for sealing annular pistons for use in actuating components such as wet disc brakes, or disc-type clutches.